Over the past three decades flexible intermediate bulk containers, commonly known as bulk bags, have gained increasing acceptance in the transportation, storage, and discharge of dry, flowable solids. Bulk bags are almost universally constructed from woven polypropylene panels which are joined along their adjacent edges by sewing. Although tubular bulk bag constructions are known, most of the present bulk bag designs are square or rectangular in horizontal cross section.
Because they are constructed from flexible fabrics, conventional bulk bag designs assume a cylindrical configuration when filled regardless of their original horizontal cross-sectional configuration. This is undesirable because cylindrical configurations cannot completely fill a square or rectangular vehicle or warehouse.
The foregoing problem is overcome by the bulk bag disclosed and claimed in the Derby Patent Number 5,076,710 issued Dec. 31, 1991, and assigned to the assignee hereof. As illustrated in FIGS. 1 and 2 hereof, the bulk bag of the Derby Patent employs side panels which are joined at seams located at spaced intervals relative to the corners of the bulk bag. Baffles extending across the corners of the bulk bag and secured to the side panels prevent the bulk bag from assuming a cylindrical configuration when filled.
The bulk bag of the Derby Patent operates satisfactorily when used in conjunction with relatively light materials. However, when used in conjunction with more dense materials, the bulk bag construction of the Derby invention is not entirely successful in maintaining a rectangular configuration when filled. Thus, a need exists for further improvements in the art of bulk bag design to provide a bulk bag which maintains a rectangular configuration even when filled with coins and other objects formed from relatively heavy metals.
The present invention comprises a bulk bag construction which fulfills the foregoing and other objectives long since found lacking in the prior art. In accordance with the broader aspects of the invention, a bulk bag constructed generally in accordance with the disclosure of the above-identified Derby Patent is provided with at least one additional panel extending between the side walls of the bulk bag. The use of the additional panel in the construction of the bulk bag prevents the side walls of the bulk bag from bulging outwardly when the bulk bag is filled with dense materials.
In accordance with more specific aspects of the invention, the bulk bag may be provided with either one or two panels extending between the side walls thereof. When two panels are used, the panels may be deployed either in a parallel configuration or in a perpendicular configuration.